Perhalophenyl Three-Coordinate Gold(I) Complexes as TADF Emitters: A Photophysical Study from Experimental and Computational Viewpoints

Abstract

We report the synthesis of novel perhalophenyl three-coordinated gold(I) complexes using 1,2-bis(diphenylphosphino)benzene (dppBz) as the chelating ligand and [AuR(tht)] (R = C₆F₅, C₆Cl₂F₃, C₆Cl₅) as the perhalophenyl–gold(I) source, leading to [AuR(dppBz)] (R = C₆F₅ (1), C₆Cl₂F₃ (2), C₆Cl₅ (3)) complexes. The solid-state structures of compounds 2 and 3 consist of discrete three-coordinated Au(I) complexes, which show a distorted trigonal planar geometry for the gold center with dissimilar Au–P distances. The distorted structural arrangement is closely related to its photophysical properties. The studied complexes display very intense emissions at room temperature (RT) and at 77 K in the solid state. Studies of the emissive properties of the complexes at different temperatures suggest that the emissions are phosphorescent at 77 K and exhibit thermally activated delayed fluorescence (TADF) at RT. First-principle calculations of the photophysical processes yielded rate constants for intersystem crossing and reverse intersystem crossing that are in excellent agreement with experimental data.